Vacuum insulator



June 1 1926.

w. G. HUSKEEPER VACUUM INSULATOR Filed Nov.

Patented June l, 1926.

UNITEDSTATES PATENT OFFICE.

G. HOUSKEEPEB, iF NEW YORK, N. Y., ASSIGNOR T WESTERN ELECTRIC COMPANY, INCORPORATED, 0F NEW YORK, N. Y., A COBPORATON 0F NEW YORK.

VACUUM INSULATOB.

This invention relates to devices for in sulating conductors of high voltage, high frequency circuits and pertains more especially to insulating devices adapted for use s in conducting the lead wires of the grid and :anode electrodes of a high power vacuum tube through the base thereof.

In employing a vacuum tube in certain installations, particularly in high voltage, high frequency clrcuits, it is necessary to provide s ecial means for preventing corona effects a ong and discharges from the lead wires of the grid and anode electrodesof the tube. Heretofore, attempts have been made to prevent these defects by surrounding the lead wires with bodies of insulating material eX- tending through the disc forming a portion of the base for vthe tube. However, the dielectric losses due to the high voltage, high' frequency currents produce suicient heating' of these bodies to quickly destroiy; their insulating property and thus render t e tube inoperative.

It is an object of this invention to provlde an insulator for use in the base of a hi h-v power vacuum tube for conducting the grid and anode lead wires therethrough whichv will effectively prevent-discharges from and v corona effects along" said lead wir'es and in which therewill he the dielectric.

` 'A further object of the invention is topro- Avide aninsulator for general use in high voltage,y high frequency circuits which is I6 simple in construction and highly eiiicient Ain operation.

To accomplish these objects and to iinprove generally upon ldevices of this character, the insulatorscomprise two ,concentric- '40 ally arranged cylinders joined-tovv ether at their extremities to form a toroi al space which is evacuated. The conductor to be insulated passes -through the inner cylinder and the evacuated space provides the necessary insulation. This device may be mounted wherever it is desired to utilize its insulating property. For example, it may be mounted in the base of a vacuum tube and a lead wire for an electrode thereof may be passed through the inner cylinder.

Other ob'ects and advantages of this in- *vention wil be apparent in the following specification and appended claims.

This invention will be better understood by reference to the following specification no injurious heating of .lower edgeof the she v'cylindrical anode 15 from which are supported the blocks 16 of insulating material between which are mounted the grid 17 and the cathode' 18 according to the manner dis- 70' closed in applicants Patent No.` 1,536,855,

dated May 5, 1925. Extending from the stem 12 tol the end of the neck 11 are the tubular members 19 yand 20, the inner ends of which are in communication with the interior of the bulb. Ar'- ranged in said tubular members are the grid and anode lead wires 21 and 22 to which are sealed the outer ends of said tubular members'. Mounted on the neck 11 of the bulb and cemented thereto is the metallic shell 23 in the lower end ofwhich is carried the disc 24 of insulatingmaterial, having a groove 25 in its peri hery into which the 23 projects. In the disc 24 are provided two apertures wherein vare arranged the insulators 26 which are cemented to the disc. Each of these insulators comprises a vessel lof'insulating material preferably glass, which is composed of inner and outer -cylinders joined together at their ends to form atoroidal space, A flange 27 is provided onthe vessel by means of which the vessel may be located relative to the disc. The ends ofthe vessel are of considerably less diameter than the mid portion thereof and on the exposed end of the vessel is mounted a cap 28. The insulators 26 extend below the disc 24 a relatively reat distance and the caps 28 are of as a'r e diameter as is consistent with the size of -t le insulators. The large diameter of the caps prevents corona effects and the distance be-v tween the caps and the disc prevents flashing from the caps to the shell or the cathode electrode. The lead Wires 21 and 22 pass throughA the inner tube of these vessels and through apertures in the caps-28 to which they are soldered. Arranged around the inner cylinder of each vessel is a shell 29 of conducting 110 manner. The disc 24 is also provided with contact members 31 having apertures throu h which pass the lead wires 32 of the cathode 18 which arel soldered to the members 31, said lead wires being enclosed in the glass tubes 33.

The base is assembled with the bulb of a vacuum tube as follows: The contact members 31 and the insulatorsA 26 with the caps 28 mounted thereon and the wires 30 joined to the caps are placed in the disc.

Next the disc is attached to the shell 23 by spinning the edge thereof into the groove 25. The base is then slipped on to the neck of the bulb, the lead wires 21 and22 of the grid and anode being-threaded through the inner cylinders of their respective insulators 26 and the lead wires 32 of the cathode being threaded through. the contact members "31,

after which the ends of the lead wires are soldered to the caps and contact members and are flushed olf. The operation of attachving the base to the bulb is performed in the olpen air and, therefore, the pressiire'against t e inner and outer`walls of the inner and outer cylinders respectively ofthe insulators is approximately atmospheric.

In Figure 2 wherein the insulator is disclosed in its adaptation for general use, 34 designates a support or member from which the conductor is to be insulated, for example, a partition or thelike.- The vessel 85 is of the same general contigurationasi26. and visrovided with a similar flange 36.' yThe conuctor 37 passes through the innercylinder and is electrically connected to the shield 38 arrangged around said inner cylinder by the wire These insulatorswhen usedin thebases o f vacuum tubes allow' thertubes to be operated 1n high voltage, high frequency circuits. The evacuated space between the two tubular members comprising the vessel prevents the high volta e, high frequency currents from causing a eating of the dielectric and thus reserves the insulating property thereof. e electrostatic field between the shield and the ground potential of the member supsorting the outer tube is not eective to prouce discharges from or corona effects along the shield as there is no gas between them to be ionized. Thel shield and the conductor to be insulated are electrically connected in o rder to maintain them at the same pol rutlal.

As a result of their both being at the same potential there is no electrostatic field between them and, consequently, there is no ionization of the as surrounding the conductor. The possibiity of corona effects along the conductor 'is thus effectively prel of the invention as defined in the appended claims.

'What is claimed is 1. A device of the character described comprising an evacuated vessel composed of inner and outer coaxial cylinders of insulating material joined together at their ends, means for supporting said vessel and an electrical .conductor passing through said inner cylinder.

2. A device of the character described comprising an evacuated vessel composed of inner and outer coaxial cylinders of insulating material joined together at their ends, means for supporting said vessel, an electrical conductor passing through' the inner cylinder, a thin shell of conducting material in said vessel surrounding said inner cylinder, and means electrically connecting said shell and said conductor.

3. In an electrical device, a glass bulb, a metallic shell surrounding a portion of said bulb, an insulating disc mounted in said shell, an evacuated'vessel of insulating material supported by said disc, said vessel comprising inner and outer coaxial cylinders of insulatinor material joined together at their ends, an -a leading-in wire for lsaid device passlng through said inner cylinder.

4. In an electrical device, a glass bulb,` a metallic shell surrounding a portion of said bulb, an insulating disc mounted in said shell, an evacuated vessel of insulating material supported by said disc, said vessel comprising inner and outer coaxial cylinders of insulating'material joined together attheir ends, a leading-inswlre for sald device assing through said cylinder, a thin shel of conducting material in said vessel surrounding said inner cylinder, and means electrically connecting said shell and said leadingin wire.

5. In an electrical device, a glass bulb, a metallic shell4 surrounding a portion of said bulb, an insulating disc mounted in .said shell, an'evacuated vessel of insulatin 4material supported by lsaid disc, said vesse comprising inner and outer coaxial cylinders of insulating material joined together at their ends, a leading-in lwire for said device passing through said inner cylinder, a metallic cap mounted on the end of said vessel and electrically connected to said leading-in wire, a thin shell of conducting material surrounding said inner cylinder, and means electri-` cally connecting said shell and cap.

In Witness whereof, I hereunto subscribe my name this 19th day of November A. D., 

